1. Field of the Invention
The present invention relates to a tooth profile for a positive hub-shaft connection with an essentially rectangular or trapezoidal groove cross section.
2. Background Description
Parallel key or sliding feather key connections are often used for the positive connection of a hub with a shaft. If large torques are to be transmitted and a displacement is to be rendered possible between hub and shaft, a multiple-groove profile or a spline shaft is often used.
The grooves thereby often have either a rectangular or a trapezoidal profile. The profiles are thereby produced either by machining or by cold forming, such as, e.g., by impact roll methods. Compared to machining, cold forming has above all the advantage of greater cost-effectiveness with large quantities to be produced.
Particularly with cold forming, in the production of such profiles a number of parameters are of crucial importance for the precision of the profile. These are in particular the diameter, the tooth thickness, the pitch, the groove flank or tooth flank shape and direction, the ovality of the workpiece, etc. The fits of these individual parameters ultimately accumulate into fit errors between hub and shaft, which are significant for an effective connection between hub and shaft. These fits are therefore to be designed with sufficient play in order to make a connection possible at all. However, this necessary play now leads to a reduction in the quality of the mating between hub and shaft, which has a negative impact, depending on the parameters and application purpose of the connection. In the subsequent cold forming, the quality requirements for these workpieces can often be met only to a qualified extent due to the inhomogeneities of the raw material.
These problems can occur with clutch disk carriers for automatic transmissions for vehicles or, e.g., markedly in the production of drive-shaft telescopic tubes, which are used in large numbers, e.g., in vehicle construction. Respectively one inner tube and one outer tube with corresponding profiling on the inside or outside are used. Due to the large production runs, the cold working method is very important for an economic production, but very high demands are made on the precision of the profile connection between inner and outer tube due to the high rotational speed of drive-shaft telescopic tubes during operation.
In the use of conventional profiles, a buckling play develops between the two tubes, caused by the usually large profile length, which in operation can lead to unacceptable radial movements of the drive shaft, which can go as far as the destruction of the drive shaft at high loads and rotational speeds. The buckling play is caused by the radial play between the profile of the inner and outer tube.